Light emitting diode

ABSTRACT

An exemplary lens includes a periphery acting as a light output surface of the lens, a light input surface surrounded by the light output surface, and a reflecting surface recessed downwardly towards the light input surface and surrounded by the light output surface. A top end of the reflecting surface connects with the light output surface. 
     The reflecting surface extends downwardly and inwardly from top to bottom. Light emitted from the light source travels into the lens from the light input surface; a part of the light directly travels out the lens from the light output surface, and the other part of the light is arrived to the reflecting surface and reflected back to the lens by the reflecting surface and travels out the lens from the light output surface.

BACKGROUND

1. Technical Field

The disclosure generally relates to light sources, and more particularlyto a light emitting diode (LED) having a secondary optical element whichcan increase light intensity of light from an LED chip at a lateraldirection whereby the LED can have a wider range of illumination.

2. Description of Related Art

LEDs have many beneficial characteristics, including low electricalpower consumption, low heat generation, long lifetime, small volume,good impact resistance, fast response and excellent stability. Thesecharacteristics have enabled the LEDs to be widely used as a lightsource in electrical appliances and electronic devices.

A conventional LED generally generates a smooth round light field with aradiation angle of 120 degrees (±60 degrees). The light emitted from theLED is mainly concentrated at a center thereof. The light at a peripheryof the LED is relatively poor and can not be used to illuminate.Therefore, the LED cannot be used in a lamp which requires a wideillumination rage, for example, an explosion-proof lamp which may be asafety miner's cap lamp or a gas station canopy

What is needed, therefore, is an improved LED which overcomes the abovedescribed shortcomings

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of an LED according to an exemplaryembodiment of the present disclosure.

FIG. 2 is an isometric view of the LED of FIG. 1.

FIG. 3 is an inverted view of the LED of FIG. 2.

FIG. 4 is a front view showing light paths of the LED of FIG. 2.

FIG. 5 is a luminous intensity curve graph of the LED of the presentdisclosure.

DETAILED DESCRIPTION

An embodiment of an LED in accordance with the present disclosure willnow be described in detail below and with reference to the drawings.

Referring to FIG. 1, an LED 100 in accordance with an exemplaryembodiment of the disclosure includes a base 10, an LED chip 20 mountedon the base 10 and a lens 30 covering the LED chip 20 and engaging withthe base 10.

Referring to FIGS. 2-3, the lens 30 includes an engaging portion 31 andan extending portion 32 extending from a top end of the engaging portion31. The engaging portion 31 and the extending portion 32 are integrallyformed and coaxial. The lens 30 is made of a material with high lighttransmittance, for example, glass, PMMA (poly ethylinethacrylate) or PC(polycarbonate).

The engaging portion 31 is cylindrical. A periphery of the engagingportion 31 is a first light output surface 311 of the lens 30. Adiameter of the engaging portion 31 increases from a bottom surface 312of the engaging portion 31 to the top end thereof, which connects withthe extending portion 32.

A receiving chamber 3120 is recessed from a center of a bottom surface312 of the engaging portion 31 to receive the base 10 therein. From topto bottom, the receiving chamber 3120 includes a first receiving part3121 and a second receiving part 3122 communicating with the firstreceiving part 3121. The first receiving part 3121 is annular to receivethe LED chip 20 therein. The second receiving part 3122 is square toreceive the base 10 therein. A width of the second receiving part 3122is similar to a diameter of the first receiving part 3121. The firstreceiving part 3121 and the second receiving part 3122 are coaxial. Atop edge 313 of the first receiving part 3121 includes a first lightinput part 3131 and a second light input part 3132 enclosing the firstlight input part 3131. The first light input part 3131 is circular. Thesecond light input part 3132 is annular and extends outwardly andupwardly from an outer periphery of the first light input part 3131. Thetop edge 313, an inner surface of the first receiving part 3121, and aninner surface of the second receiving part 3122 cooperatively form alight input surface 36 of the lens 30 to guide light generated by theLED chip 20 to enter the lens 30.

Two protrusions 3123 extend downwardly from opposite sides of the bottomsurface 312 and are spaced from each other. Each protrusion 3123 has anarc-shaped outer surface and a rectangular, flat inner surface oppositeto the outer surface. The outer surfaces of the protrusions 3123 arecoplanar to the first light output surface 311. The inner surfaces ofthe protrusions 3123 are parallel to and spaced from each other. Acutout 314 is defined between the protrusions 3123 to guide the base 10into the second receiving part 3122. Two poles 3124 each extenddownwardly from a center of a bottom surface of a correspondingprotrusions 3123. Each pole 3124 is a cylinder for engaging in asubstrate, such as a printed circuit board (not shown) to mount the lens30 on the printed circuit board.

The extending portion 32 is a frustum. A diameter of the extendingportion 32 increases from a bottom end connecting the engaging portion31 to a top end away from the engaging portion 31. A periphery of theextending portion 32 is a second light output surface 321 of the lens30. The bottom end of the extending portion 32 is larger than the topend of the engaging portion 31. A step 315 is formed at a joint of thetop end of the engaging portion 31 and the bottom end of the extendingportion 32. The first light output surface 311 and the second lightoutput surface 321 cooperatively form a light output surface 38 of thelens 30.

A central portion of the top end of the extending portion 32 is recessedto define a groove 324 therein. The groove 324 has a bottom point 3230aligned with a center of the first input part 3131. The lens 30 issymmetrical about a central axis of the lens 30, wherein the centralaxis of the lens 30 extends through the bottom point 3230 and the centerof first input part 3131. The groove 324 is funneled and a bore diameterthereof generally increases from the bottom point 3230 to a top endthereof away from the bottom point 3230. A top surface of the lens 30defining the groove 324 is a reflecting surface 323 which reflects mostof light impinging on the reflecting surface 323 to the light outputsurface 38. As clearly shown in FIG. 1, a profile of a section of thereflecting surface 323 beside the bottom point 3230 is curved and convexupwardly and inwardly. A cross section of the reflecting surface 323 isgenerally V-shaped. A curvature of the convex of the reflecting surface323 is varied between 0.0642 to 0.1920.

A transition surface 3232 is formed on the top end of the groove 324 andan inner edge thereof connects a top edge of the reflecting surface 323.The transition surface 3232 extends upwardly and outwardly from the topedge of the reflecting surface 323. A connecting surface 3233 smoothlyconnects the transition surface 3232 and the second light output surface321. The reflecting surface 323, the transition surface 3232, and theconnecting surface 3233 are reflective. A reflective material can becoated on the reflecting, transition and connect surfaces 323, 3232,3233, whereby a light reflectivity of these surfaces is larger than alight perviousness thereof. .

Referring to FIG. 4, during operation of the LED 100, light emitted fromthe LED chip 20 travels into the lens 30 from the light input surface 36of the lens 30. A part of the light is arrived at the first light outputsurface 311 and the second light output surface 321 and directly travelsout of the lens 30, and another part of the light is arrived at thereflecting surface 323, the transition surface 3232 and the connectingsurface 3233.

Most of the another part of the light is reflected by the reflectingsurface 323, the transition surface 3232 and the connecting surface 3233and travels towards the first light output surface 311 and the secondlight output surface 321 to radiate therefrom to leave the lens 30.Thus, the LED 100 has a radiation angle more than 120 degrees.

Referring to FIG. 5, an illumination intensity distribution of the LED100 is shown wherein an N line shows a luminous intensity curve asviewed from the front side of the LED 100, while an M line shows aluminous intensity curve as viewed from a top view of the LED 100 whichis perpendicular to viewing aspect of the N line. The M line shows thatlight is evenly distributed at a surface perpendicular to the centralaxis of the LED and forms a similar circular projection. The N lineshows the radiation of the LED 100 is larger than 180 degrees. About 90%light emitted from the LED 100 is distributed in a region between 170°to 190°, and only a small light is distributed in a region between 10°to 160°; thus, a light intensity at a lateral side of the LED 100 isenhanced and an illumination range of the LED 100 is increased.

It is to be further understood that even though numerous characteristicsand advantages of the present embodiments have been set forth in theforegoing description, together with details of the structures andfunctions of the embodiments, the disclosure is illustrative only, andchanges may be made in detail, especially in matters of shape, size, andarrangement of parts within the principles of the disclosure to the fullextent indicated by the broad general meaning of the terms in which theappended claims are expressed.

What is claimed is:
 1. A lens adapted for adjusting light emitted from alight source whereby light intensity at a lateral side of the lightsource is increased, the lens comprising: a periphery acting as a lightoutput surface of the lens from which the light entering the lens leavesthe lens; a light input surface surrounded by the light output surface,configured for receiving the light from the light source; and areflecting surface recessed downwardly towards the light input surfaceand surrounded by the light output surface, a top end of the reflectingsurface connecting the light output surface, a bottom end of thereflecting surface located over a center of the light input surface, thereflecting surface extending downwardly and inwardly from the top end tothe bottom end, a light reflectivity of the reflecting surface beinglarger than a light perviousness thereof; wherein the light emitted fromthe light source travels into the lens from the light input surface, apart of the light directly travels out the lens from the light outputsurface, and the other part of the light is arrived to the reflectingsurface and reflected back to the lens by the reflecting surface andtravels out the lens from the light output surface.
 2. The lens of claim1, wherein a groove is defined in a top end of the lens, and a topsurface of the lens defining the groove forms the reflecting surface ofthe lens.
 3. The lens of claim 2, wherein the groove is funneled and abore diameter thereof generally increases from bottom to top.
 4. Thelens of claim 3, wherein a profile of a section of the reflectingsurface beside the bottom end of the reflecting surface is curved andconvex inwardly and upwardly.
 5. The lens of claim 3, wherein acurvature of the profile of the section of the reflecting surface isvaried between 0.0642 and 0.1920.
 6. The lens of claim 3, wherein atransition surface extends upwardly and outwardly from the top edge ofthe reflecting surface and a connecting surface smoothly connects thetransition surface and a top end of the light output surface.
 7. Thelens of claim 1, wherein the lens comprises an engaging portion and anextending portion extending from a top end of the engaging portion, theengaging portion and the extending portion are integrally formed andcoaxial.
 8. The lens of claim 7, wherein a periphery of the engagingportion and a periphery of the extending portion cooperatively form thelight output surface of the lens.
 9. The lens of claim 8, wherein theextending portion is a frustum and a diameter of the extending portionincreases from a bottom end connecting the engaging portion to a top endaway from the engaging portion.
 10. The lens of claim 9, wherein thebottom end of the extending portion is larger than the top end of theengaging portion, and a step is formed at a joint of the top end of theengaging portion and the bottom end of the extending portion.
 11. Thelens of claim 9, wherein the reflecting surface is defined in a centralportion of the top end of the extending portion.
 12. The lens of claim7, wherein the engaging portion is cylindrical, and a diameter of theengaging portion increases from a bottom end away from the extendingportion to the top end connecting the extending portion.
 13. The lens ofclaim 12, wherein a receiving chamber is defined in the bottom end ofthe engaging portion, and an inner periphery of the receiving chamber isthe light input surface of the lens.
 14. The lens of claim 12, whereintwo protrusions extend downwardly from opposite sides of the bottom endof the engaging portion and spaced from each other to define a cutouttherebetween, the cut being configured for guiding the light source intothe receiving chamber.
 15. The lens of claim 14, wherein two polesextend downwardly from the protrusions respectively, the two poles beingconfigured for engaging in a mounting device.
 16. An LED comprising: abase; an LED chip mounted on base; and a lens covering the LED chip andengaging with the base, the lens comprising a periphery acting as alight output surface of the lens, a light input surface surrounded bythe light output surface, and a reflecting surface recessed downwardlytowards the light input surface and surrounded by the light outputsurface, a top end of the reflecting surface connecting the light outputsurface, a bottom end of the reflecting surface being located over a topof the light input surface, the reflecting surface extending downwardlyand inwardly from the top end to the bottom end, a light reflectivity ofthe reflecting surface larger than a light perviousness thereof; whereinlight emitted from the LED chip travels into the lens from the lightinput surface, a part of the light directly travels out the lens fromthe light output surface, and the other part of the light is arrived tothe reflecting surface and reflected back to the lens by the reflectingsurface and travels out the lens from the light output surface.
 17. Thelens of claim 16, wherein the reflecting surface is funneled and a borediameter of the funnel generally increases from bottom to top.
 18. Thelens of claim 17, wherein a profile of a section of the light reflectingsurface beside the bottom end is curved and convex inwardly and upwardlyand a curvature of the profile of the section of the reflecting surfaceis varied between 0.0642 and 0.1920.
 19. The lens of claim 16, wherein areceiving chamber is defined in a bottom end of the lens, and the LEDchip and the base are received in the receiving chamber.
 20. The lens ofclaim 19, wherein an inner periphery of the receiving chamber is thelight input surface of the lens.